摘要
The aim of the present experiment was to study foraging behaviour of pigs with the perspective of using this as a resource in a cropping system. Twenty crossbred growing pigs, divided into four groups, were observed for three experimental weeks during the summer of 1995 at Ekhaga Research Farm east of Uppsala. The pigs had an adaptation period of three weeks to outdoor conditions on a grass pasture and were then introduced to a second year clover/grass pasture after a first cutting. Foraging behaviour was studied in relation to stocking rate (five pigs on 50 m2/week or 100 m2/week) and crude protein level in the feed (137 or 191 g CP per kg dry matter). The behaviour of each individual pig was recorded instantaneously at 1 min intervals, for four 20-min periods per day during four successive days on each treatment in all experimental weeks. Weather conditions, herbage mass and soil moisture were recorded. The frequencies of eating were lower and nosing and other activities higher on the 50-m2 plots compared with the 100-m2 plots, whereas rooting and passive behaviour tended to be higher on the 50-m2 plots. Crude protein level in the feed did not influence any of the behaviours. Passive behaviour increased from day to day within the observation weeks and an interaction between observation week and observation day for eating and other activities was found. An increase in eating could be related to the amount and quality of herbage and resulted in lower levels of passive behaviour and other activities. Rooting was constant in relation to air temperature, whereas eating decreased with increasing temperature. However, rooting in the drinker/wallowing area increased at a temperature around 20°C, indicating a shift from ‘foraging rooting' to ‘comfort rooting' digging out the wallowing area. The results suggest that growing pigs have a priority for grazing, when clover/grass of good quality is available, in periods with hot and dry weather.